A new method has been developed to study the interactions of DNA repair enzymes with fluorescent oligonucleotides bound to beads (Shen et al. submitted to Biochemistry). We have identified important regions in the human flap endonuclease responsible for binding and enzymatic activity (Shen et al., JBC, in press). We are developing a detailed analysis of enzyme activity on particles for single turnover kinetics (Nolan et al., in preparation). See Nuclease research highlight.